Sorry, but I don't understand what you mean by "non-crossable board position". Do you mean non-jumping? That would be nD or nH. But in the Interactive Diagram it is imperfectly implemented, and for leaps that are too large it would not work correctly.
Sorry, but I don't understand what you mean by "non-crossable board position". Do you mean non-jumping? That would be nD or nH. But in the Interactive Diagram it is imperfectly implemented, and for leaps that are too large it would not work correctly.